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Sort of. GPS-tagging works, but without network access, it takes about a minute to find your location (same as any car GPS if you move it while turned off). With network access, the phone can use so-called A-GPS to improve that time to seconds, which is what you usually see. The first photos you take might get the wrong location until the phone figures out where it is.

What is stored in the photo is always the GPS-coordinates - the location for them is then figured out in the viewer app.

The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.

I'll admit to never testing this in practice, but I believe that what happens is that the first photo or so gets the coordinate of the last time the phone located itself. A-GPS will work if you simply leave the phone connected to the cell phone network even if you completely disable mobile data and never use it for phone calls and texts, so I suggest you just do that.

The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.

My suggestion is also leave your sim card in your phone but turn off roaming or anything related to data. The phone will be able to find roaming partner cell signals and display it on your top left screen corner. That way, you can still get A-GPS coordinate without using any data, plus plenty of free msg from those carriers to promote their service, in some countries.

Not sure if phone call will be blocked though, if that's what you want to avoid.

Best approach is to have your iPhone unlcoked and use a cheap local prepaid sim card in many European countries.

Sort of. GPS-tagging works, but without network access, it takes about a minute to find your location (same as any car GPS if you move it while turned off). With network access, the phone can use so-called A-GPS to improve that time to seconds, which is what you usually see.

Interesting, but my experience suggests otherwise. If I take my dedicated GPS on a flight to somewhere far from where it was last turned on, it figures things out after about a minute. In that case it has the almanac and the time, but no idea of the position. There is a note in that article that some devices can shorten that cold start time by using multiple channels - perhaps that's what's happening here.

The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.

Cold start is very worst case. Most GPS units have sufficiently accurate internal clocks that being off for even a few days won't get you to that bad a situation if the location is still relatively near the last fix. There's where the "unknowns" creep up. The GPS unit uses the current time to look up what satellites should be visible from the last known location. With an accurate clock but a large distance between current location and the last fix, the unit will look for the wrong satellites, and that can slow things down immensely.

Cold start means the unit (or phone) has NO time information, and a GPS unit will start essentially polling ALL satellites for a time signal. There are at least 30 GPS satellites, counting hot spares, and they broadcast their time signal every 30 seconds, so depending on when in that 30 second window the unit starts looking, it could have to go through the whole list more than once before getting lucky and polling a satellite that should be visible.

Having a fairly recent cell connection, or a WiFi connection with time information, an iPhone should be able to find satellites more quickly than worst case, and if the WiFi provides the phone with sufficient location data, it can help the GPS system in the phone look for the right satellites at the right time.*

A couple years ago I was at Roatan Island in Honduras, and I had my international roaming option turned off to avoid charges; my GPS app, MotionX GPS, couldn't even get a clue where I was, since the phone had been turned off for a couple of days. But when I turned on the cell service, MotionX locked on in 20-30 seconds. I would assume that this would be an indication of how the internal GPS system reacted without, and then with cell service as a "seed" for coarse location determination.

*I'll admit a complete lack of knowledge of how basic WiFi networks provide either time or location information that iPhones can use, and I'd appreciate pointers to where I can read up on this.

Basically, someone sits in a car with a GPS and a WiFi antenna, driving along all streets and logging which networks can be "seen" from any location. These days the data comes from many sources - in Apple's case, I believe that iPhones report data like this in anonymized form to build Apple's database.

The new Mac Pro has up to 30 MB of cache inside the processor itself. That's more than the HD in my first Mac. Somehow I'm still running out of space.